Red Witch Synthotron Analog Synth Pedal Review

For guitarists who dig the
electronic sound of a synthesizer,
guitar synth pedals
can combine the best of both
worlds—the psychedelic glow,
glitchiness, and fat tones of
a synth’s oscillators with the
expressiveness of guitar strings.
There are a handful of such
devices on the market that use
a guitar signal to drive synth
oscillators inside a pedal. And
depending on the implementation,
the results can range from
swooping UFOs, to buzzing
leads, to chugging synth bass.

Synth pedal controls and
parameters can differ wildly
and prioritize different aspects
of synthesis. Red Witch’s
Synthotron, which is a synthesizer,
sample and hold, and
envelope filter, takes an ambitious
but streamlined approach
by packing a lot of sound-sculpting
features into a box
that can be a handful at times,
yet yield spectacular results.

Expansive Synth Controls
Outwardly, the Synthotron is a
delicious fusion of ’70s graphical
concepts (there’s more than a
few hints of Mu-Tron design in
the multi-colored enclosure) and
Red Witch’s forward-thinking
design notions. The pedal is built
around a synth engine divided
into three sections—octave up,
octave down, and tremolo—as
well as a filter section. Each section
is assigned its own colored
block, which helps orient you
on the fly. The left footswitch
engages the filter and its
controls located
on the right side
of the pedal (which
is a tad counterintuitive),
while the right footswitch
engages the synth section. And
being able to run either side
independently or in combination
really opens up the sonic
possibilities of the Synthotron.

On the Synth Side
The Synthotron is a 2-channel
synth pedal, which means that
the tracked pitch from your
guitar controls the pitch of two
separate square-wave oscillators.
Square waves are a common
choice in synth pedals because
they sound buzzy—not unlike a
distorted guitar—but also have
a very evocative video game-like
sound, which can be heavy,
funky, or hilarious depending
on how you use it. The
Synthotron’s square-wave tone,
however, is a fat, rich foundation
for tweaking.

The first channel can be set
to one or two octaves up, and
the second channel can be set
to one or two octaves down.
Each octave channel has a dry
level knob, which controls the
balance of effected and clean
signal, and a decay knob that
dictates the sustain of the synth
signal. The last effect on the
synth side is a tremolo channel
that, like the octave-up and
octave-down channels, can be
bypassed via a mini-toggle.

The filter section controls
an envelope filter that produces
an auto wah-like effect and
the range control determines
whether the sweep occurs across
higher or lower frequencies.

There’s also a sample-and-hold
switch, which overrides the
envelope. This moves the filter
position around in an unpredictable,
floating fashion. There’s also
a control that sets the speed of
the sample-and-hold generator.
Faster settings produce the sound
of a robot in deep thought.
Slower settings bring to mind
the drifting, psychoactive states.

Gateway to Gonzo
One of the most important
qualities of any pitch tracking
effect is its ability to accurately
register the pitch of your instrument’s
signal. Some players
want 100-percent perfect pitch
tracking. Other players prefer
the quirky, less-stable pitch
tracking common with vintage
analog synths. The Synthotron’s
tracking injects just enough of
that vintage quirkiness while
remaining musical. The pedal
also has an internal trim pot
that allows you to adjust the
pitch tracking sensitivity.

Because the synth tones
are generated by the pedal
itself, pickup selection on
your instrument will not
impact the actual synth
sound. Pickup selection does
produce slight variation in
pitch tracking though, though
my Strat’s single-coils tracked
with ease, and my Gibson SG’s
meatier humbuckers tracked
more reliably than single coils.
In any case, the Synthotron’s
wet/dry control allows you
to create an effect that blends
in a subtle amount of square-wave
buzz. Independent level
controls for each of the two
oscillators allow you to mix low
and high octaves like you would
with any flexible octave pedal.

The Verdict
The Synthotron packs a lot of
analog synth power into a small
package. Given its small size,
the pedal’s ability to perform
dual-voice analog synthesis,
tremolo, filtering, and sample-and-hold is impressive. The
independent mixing controls
give the player the ability to
strap on their chef ’s hat and
adjust signals to taste. Analog-synth
fans will appreciate the
pure analog circuitry of both
the pitch tracking circuits as
well as the oscillators.

And when you’re looking to
step away from the synth, the
Synthotron’s filtering channel
can be used independently for
funky, envelope-filtering effects.
All these tone permutations, plus
each effect’s ability to go from
tame to unhinged, makes the
Synthotron not just powerful,
but practical and musical as well.

At the University of Iowa, Lyle majored in Computer Science, but his most prized possession was a key to the school's Electronic Music Studios. With his home studio he has produced music and provided sound design for film, radio, and podcasts. Lyle's current musical obsession involves integrating electric guitar signals into his modular synthesizer. He is a software developer by trade and finds it fulfilling to use that skill to help build better healthcare systems. He lives in an old house in Iowa next to the Mississippi River with his wife and their retired racing greyhound, Yeti.

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